四分律比丘含注戒本 2.808

2.808

佛在釋翅瘦。難陀短佛四指，比丘遙見，謂佛奉迎，至乃知非，各懷慚愧。佛制難陀著黑衣。六群與佛等量或過量作，比丘舉過，佛因制戒。

The Buddha was among the Śākyas. Nanda was shorter than the Buddha by four fingerbreadths. When the bhikṣus saw him from afar, they thought he was the Buddha and went out to welcome him; only upon reaching him did they know he was not, and each felt ashamed. The Buddha ordained that Nanda wear dark-colored robes. The group-of-six made robes equal in measure to the Buddha's or exceeding the measure. The bhikṣus reported the fault, and the Buddha thereupon formulated the precept.